Vascular therapy can encompass many medical treatments to the vascular system. One example is the general systemic administration of a therapeutic agent within a body vessel. Although many medical conditions are satisfactorily treated by the general systemic administration of the therapeutic agent, the treatment of many conditions require delivery of the therapeutic agent locally within a body vessel. More specifically, delivery of the therapeutic agent is to only a selected portion of internal body tissue, without delivering the therapeutic agent to surrounding tissue or requiring additional systemic delivery of the therapeutic agent. A systemically administered therapeutic agent may be absorbed not only by the tissues at the target site, but by other areas of the body. As such, one drawback associated with the systemic administration of therapeutic agents is that areas of the body not needing treatment are also affected.
Medical delivery catheters provide a minimally invasive means for delivering therapeutic agents to internal body tissue. To provide site-specific localized treatment, balloon catheters may be used to deliver the therapeutic agent exclusively to the target site within a body vessel. One example of a condition that is beneficially treated by local administration of the therapeutic agent with a balloon catheter is the delivery of the therapeutic agent in combination with percutaneous transluminal coronary angioplasty (PTCA). PTCA is a technique used to dilate stenotic portions of blood vessels. During PTCA, a catheter balloon is positioned at a blocked lumen or target site, and the balloon is inflated to cause dilation of the lumen. The balloon is deflated and the catheter is then removed from the target site and from the patient's lumen thereby to allow blood to flow freely through the unrestricted lumen.
Although PTCA and related procedures aid in alleviating intraluminal constrictions, such constrictions or blockages may reoccur in many cases. The cause of these recurring obstructions, termed restenosis, may be due to the body responding to the surgical procedure. Restenosis of the artery commonly develops over several months after the procedure, which may require another angioplasty procedure or a surgical by-pass operation. Proliferation and migration of smooth muscle cells (SMC) from the media layer of the lumen to the intima cause an excessive production of extra cellular matrices (ECM), which is believed to be one of the leading contributors to the development of restenosis. The extensive thickening of tissues narrows the lumen of the blood vessel, constricting or blocking the blood flow through the vessel. Therapeutic agents selected to limit or prevent restenosis may be locally delivered with PTCA from a catheter and/or by placement of a stent configured to release the therapeutic agent after the PTCA procedure. Catheter balloons may be used in combination with stents, synthetic vascular grafts or drug therapies during the PTCA procedure to reduce or eliminate the incidence of restenosis. Yet, some catheter balloons may occlude or block blood flow distal to the treatment site. Some perfusion balloon catheters only allow a small percentage of perfusion. For example, a balloon catheter sized for a 6 mm body vessel may only provide a 1 mm passageway.
Another type of vascular therapy is gaining hemostasis with a lacerated hole in the body vessel. During emergency procedures, quick hemostasis is desirable to prevent any more blood from leaving the body. Conventional methods of promoting hemostasis is by applying pressure over the blood vessel manually and then by applying a pressure bandage, compressive weight, or clamp device, while applying a therapeutic agent. Some devices can be implanted within the body vessel to block the lacerated hole. However, these devices are typically left permanently within the body vessel, which are likely to promote a risk of closure or acutely clot formation in only a few years, and difficult to remove otherwise.
In view of current devices and methods, there is a need for a medical device for applying vascular therapy locally within a body vessel while allowing fluid flow to areas distal to the treatment site.